1. Field of the Invention
Golf Club Shaft and Method of Making the Same.
2. Description of the Prior Art
Since approximately 1930 tapered hollow tubular golf shafts have been approved for all competition. However, from time-to-time golf shafts made from different materials have appeared, but in the main these shafts have offered no overall advantage over steel shafts. The steel golf shaft is the most common shaft now in use.
In golf it is distinct advantage to be able to hit the longest ball accurately within a given set of conditions. The distance the ball will travel is dependent on a number of variables, but primarily the mass of the golf club head impacting the ball times the acceleration of the head. The force exerted upon the impacted golf ball is thus dependent on both the mass of the golf club head and the rate of acceleration, and by increasing either of these the force could theoretically be increased. However, in actual practice if the mass of the golf club head is increased the acceleration decreases and likewise the rate of acceleration can only be increased by a decrease in the mass of the golf club head. Thus, varying these two factors does not in the overall provide an increase in the force exerted on the impacted golf ball.
The optimum configuration of a golf club is described as a "swing weight" which is measured on a special scale, and every golfer has an optimum swing weight to fit his particular physical capabilities. If the mass of a golf club head can be increased without increasing the total weight of the club head itself, then more energy can be imparted to the ball. This can only be accomplished by removing weight from the golf club shaft and/or grip, and adding this mass to the golf club head. This will increase the swing weight of a given club without increasing the total weight of the club, and will enable a golfer to impart more momentum to a ball and achieve the much desired longer ball. A second possibility is to design a shaft and head that will have a greater capability to transfer the kinetic energy of the golf club to the golf ball. If this is achieved, the ball will again fly farther under a given set of conditions. High speed photographs of a golf club swing show the effect of the ball inertia and recovery ability upon the club face itself. Kinetic energy can only be imparted to the golf ball while the club head is in contact with the ball. Several factors effect this contact.
One of these factors is the mass of the club head and the acceleration at which it is traveling upon contact with the ball. Another factor is the ability of the golf club shaft to resist a forced couple set up in the shaft as a result of the inertia of the ball imparting a resisting or opposing force to the point of impact on the golf club head. Since the centerline of the shaft is behind the point of impact, a clockwise force couple is built up in the shaft due to this eccentric loading. This causes the golf club head to rotate clockwise (looking down at the golf club head by a right-handed golfer) at the moment of impact. This action is more commonly known as "torque".
During the rest of the stroke the ball compresses until the stored energy is sufficient to overcome its inertia. The ball then begins to accelerate faster than that of the golf club head and moves away from the head. If the stored energy from the twisting couple at the moment of impact is not put back into the ball before the ball leaves contact with the golf club head then this energy will be lost. The spring rate and energy storing ability of the golf club shafts are therefore shown to be important factors in the amount of kinetic energy imported to the ball at, and subsequent to the point of impact. Also the ability of the shaft to maintain the club head in contact with the impacted ball for the longest period of time becomes the major function of the golf shaft.
Since all golfers are not the same size, do not possess the same amount of strength, it is necessary to manufacture shafts of varying lengths, weights, strengths, and flexes. These variations in shafts then enable all golfers to be fitted properly, whether they be children, men or women, young or old, weak or strong, tall or short, and amateur or professional.
Due to the wide variety and types of golf club shafts that must be manufactured to suit these innumerable demands, it is highly desirable that a single shaft could be manufactured that could be properly fit to the golf club head to provide a golf club that would suit the physical capabilities of a particular golfer.
A major object of the present invention is to supply a single shaft that is of such structure that it may be rotatably adjusted and secured to a golf club head for the shaft to have a desired stiffness against lateral flexing during the golfer's swing, will cause the golf club head to remain in contact with the impacted golf ball a maximum length of time to facilitate transfer of kinetic energy from the club head to the ball, and the shaft offering maximum resistance to rotation of the golf club head as the latter transfers kinetic energy to the struck golf ball.